This invention relates to a method to immunize domestic poultry against infectious diseases. Specifically, it relates to the inoculation of an egg with vaccines, vitamins, or other soluble materials, prior to the chicken being exposed to diseases, and to improve development at the earliest possible time.
Young chicks and poults are exposed to disease-causing agents on the first day after hatching when they enter the brooder house. Vaccination during the incubation period would allow the birds to develop partial or total immunity to infectious microorganisms prior to exposure. Birds could develop immunity at an earlier age and suffer fewer death losses in the brooder house. Currently, birds are usually vaccinated after hatching by water or aerosolization. Most of the immunizing products are first applied to birds that are several days of age and then repeated periodically. In recent years, vaccines against respiratory viruses have been aerosolized and used in older birds. Eye drop vaccination is employed to protect birds one week of age or older against infectious laryngotracheitis. The problems that exist with these methods are that such vaccination does not ensure that each bird is exposed, nor do they allow the poultry producer to control the exact dose that each bird receives.
Further, the earlier the vaccination, the less likelihood that there will be loss of poultry to infectious diseases. A major problem associated with the current poultry vaccination procedures is that baby birds are exposed to field viruses and bacteria before they have the opportunity to develop immunity. Almost without exception, a full week is required to develop a protective level of antibodies after a bird has been vaccinated. Even if birds are immunized on the first day after hatching, they are still susceptible to an infectious disease during the first seven days of life. Birds surviving an infection at such an early age frequently have impaired productivity for the remainder of their life. If chickens possessed immunity when they emerged from the egg, they would be much more resistant to disease at an early age.
Attempts have been made to immunize chick embryos, but the major difficulty involves transporting the vaccine material through the egg shell. One method which has been attempted to deliver material such as antibiotics and vaccines through the egg shell is to place warm, incubating eggs in a cold antibiotic solution. The material in the egg contracts upon contact with the cold solution, thus creating a vacuum inside the egg which causes the antibiotic fluid to pass through the pores of the egg shell to the embryo. The problem with this method is that, when done on a large scale, th antibiotic fluid becomes contaminated by microbes that are not susceptible to the antibiotic. When these microbes are pathogenic, they can infect and kill the embryos.
Another method to get the material to the embryo is to pass a needle through the shell to the embryo and inject the substance. Unfortunately, the trauma of the needle injection often kills the embryo. also, there is a relatively large hole in the shell after the needle is withdrawn. Microbes from the environment can easily enter such a large opening in the shell.
This invention improves upon the prior art by providing for a method of inoculation which forces the soluble material through the pores in the shell, without damage to the shell or the chick embryo.